4-5 mpg on 7.3 w/banks turbo

[Thewespaul]

Try advancing the pump a dime width before deciding to replace pump

 

[Chrismohan]

Try advancing the pump a dime width before deciding to replace pump

Ok

 

[Chrismohan]

Try advancing the pump a dime width before deciding to replace pump

Ok

 

[FORDF250HDXLT]

I don't think you'll see a 7-10 MPG increase simply by adjusting the engines timing.I have no idea where it would need to be set,to purposely try for 4 to 5 mpg.I'm not going to claim this is impossible but holy smokes,I sure would be some surprised.I would guess someones steeling your fuel at night first.

An IP and injectors would have to be some worn to cause this kind of fuel economy.I've heard of people letting IP and injectors go for so long,they lost a great deal of power but I've never read of an IDI pickup yielding just 4 mpg before.Something else, like a fuel crossover issue with the fuel selector valve and diesel overflowing from a tank, is about the only thing I can think of that fuel economy would look like 4 or 5 MPG.

If something really is causing the IDI to drink so much,surely only a major boost leak could be the cause?

 

[Thewespaul]

I agree that timing is not the whole issue here. Do you by chance have a stock mechanical lift pump? If so the diaphram could be ruptured and be pouring fuel into the crankcase, otherwise how are measuring your mileage?

 

[jwalterus]

Do you have a 5.43 rear with double underdrive rapping it out in 1st all the time?

4 mpg on an IDI and no power, and you said it ran better with the old injectors?

PUT 'EM BACK IN!!!!!!!!!!!!!!!!

JM2CW

 

[pelky350]

It sounds like you may have a few small things going on all at once, possibly warn pump, possible not so good quality injectors(advanced auto isn't a diesel shop) their parts aren't bad I'm saying but those are likely just old injectors that have been cleaned pop tested probably not very accurately and not matched into a set because technically they "don't have to be" to run. I would buy other things from them and do but certain things are best left to the experts in fuel system parts and such.

 

[FordGuy100]

Even with bad injectors, and timing so far off it hardly runs, I honestly can't see an IDI getting that fuel mileage. How are you calculating fuel mileage?

 

[AcIdBuRn02ZTS]

Can you post a video of how it runs.. how it revs and how it idles? If timing is THAT far off... It would be easy to hear.

I'd start off by putting a locking fuel cap on for giggles. Someone may be borrowing fuel without your knowledge.

 

[riotwarrior]

Conestoga diesel
Russ aka @typ4 here
Or justin at R&D IDI performance are the best places for pumps and or injectors...sadly anywhere else is crap shoot....

Sounds like somethings awry for sure...

 

[Shadetreemechanic]

Check your speedometer for accuracy as well. As others have said, that is really terrible mileage with no leaks and no black smoke.
Someone could have changed the rear axle out or done a transmission swap with a different speedo gear and your odometer could be underreporting.
That won't help your power issues, but it would help your mileage.

 

[Macrobb]

Something else, like a fuel crossover issue with the fuel selector valve and diesel overflowing from a tank, is about the only thing I can think of that fuel economy would look like 4 or 5 MPG.

I think this is a very likely cause.
Make sure you fill up both tanks, use the rear tank first(because if the selector valve sticks, it will stick returning to the rear tank), and then re-fill both tanks and see where you are at.

---
Your setup should be making somewhere in the 14-16 MPG range unloaded, depending on speed and what you are doing - obviously, idling it until it fully warms up and then taking short trips will take some fuel. Longer trips at medium speed(45-60mph) will probably net you the best mileage.

And, if you decide to throw a big honking truck camper on the back and go 70, well, don't expect more than about 11-12.

 

[Pullet]

My worst mileage ever was 4.5mpg on a half tank of firewood-getting in low four (zf5). Plenty of power, much torque being used as I hooked up to larger and larger chunks of trees.

You're running a turbo (on the road?) and getting that mileage with no power, which means the fuel is going somewhere but not doing you any good. Sounds like your crankcase would have overflowed by now if it was going there, unless you're burning oil fast.

No smoke implies it's not getting out the tailpipe. Do you have a catalytic (and is it glowing yellow-orange)? Otherwise my best guess is that it's leaking somewhere, got a parking brake or wheel chocks to watch it at idle, maybe a helper to rev it?

Timing sounds like something else to check, since you're getting 1/3 the mileage you should be getting with good power..

 

[chillman88]

For what it's worth, my 91 ZF5 non- turbo crew cab dually 2wd gets approximately 15mpg empty on what I believe to be the original 175k mile injectors.

 

[Chrismohan]

Thanks for all the advice. I put a new ip in and im about to do the o rings and injector caps. I hope this was the problem. It was weird because i got no black smoke, no fuel was leaking or filling the crank case or going out the tailpipe. Hopefully the pump was my issue